The evaluation of staging or post-therapy bone marrow biopsies for involvement by B cell lymphoma has traditionally been based on morphologic findings. To improve sensi¬tivity, morphologic examination is now augmented by ad¬vances in molecular technology that detect clonal lym¬phoid populations by immunoglobulin gene rearrange¬ments and lymphoma associated chromosomal translo¬cations (Coad et al 1997) molecular testing initially used Southern transfer (SB) and restriction fragment length DNA analysis to detect clonal antigen receptor gene rearrangements and translocations. Several factors make SB generally unfavorable for routine diagnostic testing, including the amount of time and labor needed, the requirement of large quantities of DNA, the reliance on radioactive probes, and the relative insensitivity to minimal disease below 5% of marrow cells (Lehman et al 1995 & Sioutos et al 1995). Development of the polymerase chain reaction (PCR) ameliorates these factors and presumably detects clonal populations below the morphologic threshold. Although clone-specific PCR methods are specific and sensitive to a level of one in 10 000 000 cells, these methods are too inef¬ficient for routine testing because unique primers are required for each patient and may fail in some leukemias and lymphomas as a result of clonal evolution (Coad et al 1997). The development of consensus primers for the hyper variable (VDJ) region of the immunoglobulin heavy chain (IgH) permits routine use of gene rearrangement studies in the evaluation of lymphocytic disorders. These assays achieve excellent specificity, although they have demonstrated a lower sensitivity than the clone-specific primers. The specific sensitivity depends on the primer set, lymphoma subtype, degree of competitive amplifi¬cation between monoclonal and polyclonal lymphocyte DNA, and tissue fixation. With a multiple primer panel, the clonality detection rate in primary diagnostic tissue is approximately 80% overall, varying with the type of non-Hodgkin's lymphoma (Coad et al 1996). The purpose of the present study is to correlate the sensitivity of morphologic and histochemical assessment of bone marrow lymphomatous involvement and PCR-based molecular studies in pa¬tients with B-lineage lymphomas. Proper staging and detection of minimal residual disease in case of B cell Non Hodgkin’s Lymphoma Results: of the 49 cases studied Out of the 35 PCR positive cases, we had twenty eight positive cases for FR III (83%), Four cases were positive for FRII (11%) and three cases were positive for both FRIII and FRII (9%). FR Ill-directed primers detect approximately 60% of clonal B cell malignancies. Conclusion: Proper staging and detection of minimal residual disease in case of B cell Non-Hodgkin’s Lymphoma using a rapid reliable technique improve the prognosis of these patients by increasing or even changing the protocol of management for the positive patient .